VOL. XXXVII.] PHILOSOPHICAL TRANSACTIONS. 509 



Experience and common reason teach the people there, that these diamonds 

 came from another place by the current of the waters, and are not the natural 

 product of the situation where they now are found. So they are using all pos- 

 sible diligence to find out the place where they grow. They have not hitherto 

 discovered it ; but their hopes are much encouraged by having near the said 

 situation several mountains, where there are abundance of fine solid rock. 

 crystals. 



The diamonds that have been found, are commonly from 1 grain to 6 carats; 

 some larger, and among these, one of 45 carats. Their colour, solidity, and 

 their other properties, are the same with those of the oriental diamonds; only 

 it was observed, that those that lay more superficially, and exposed to the air 

 and sun, were more scurfy; and consequently lost more by polishing than the 

 others. 



Meteorological Observations, made for six Years at Padua. By Sig. Poleni. 

 N° 42] , p. 201 . Translated from the Latin. 



In the first place it is to be observed, that S. Poleni, in denoting the times, 

 has, after the manner of astronomers, computed the beginning of each day 

 from noon ; and that he has made his observations a little after noon, unless 

 otherwise prevented. 



He made use of the old stile in designing the times, and of the English foot 

 and its parts, in measuring. And, if in the progress of the observations, any 

 of them be accommodated to the new stile, and French measures, he mentions 

 that alteration. 



In measuring the snow, he caused it to be melted, and then he measured it 

 in the same maimer as rain-water. The tube of his barometer is pretty large, 

 and the diameter of the cistern or vessel, containing the stagnant mercury, is 

 almost 20 times the diameter of the tube; therefore, in the ascent and descent 

 of the mercury in the tube, the height of that in the vessel may be with safety 

 considered as invariable. 



His thermometer is one of those of M. Amonton's invention, with a recurve 

 tube terminating in a phial, or ball, wliose lower part is filled with quicksilver, 

 and upper part with air; and by the greater or less dilatation of the air, accord- 

 ing to the different degrees of heat, the mercury rises more or less in the tube; 

 but because the extremity of the tube is open, the true height of the thermo- 

 meter must be compounded, of the observed height of the mercury in the 

 tube of the thermometer, and of the height of the mercury in the barometer, 

 collected together into one sum ; and that height be set down in the Epheme- 



